Field of the Invention
The present invention relates to the development of control units, such as are used in the automotive industry or in the aviation industry, for example, for controlling technical systems such as, e.g., engines or brakes. Also, the present invention relates to testing devices that are used in the development process for the control unit.
Description of the Background Art
The development of control units has become a highly complex process. New control units and new control functions should thus be tested as early in the development process as possible in order to verify general functionality and to set the direction for further development. Towards the end of the development process, it is important to test the control unit, which has already undergone extensive development, as comprehensively as possible in order to make necessary modifications based on the test results before the control unit comes into use or enters mass production, so that it functions as desired under all conditions in later operation.
Two exemplary steps of the development process in which testing devices are used for testing the control unit are described below. So-called hardware-in-the-loop simulators (HIL simulators) are employed at a fairly late stage of the development process. Such HIL simulators contain a model of the technical system to be controlled, with the model being present in software. The HIL simulator also contains an input/output interface to which it is possible to connect the control unit, which has already undergone extensive development and is physically present as hardware. The functionality of the control unit can now be tested in various simulation passes, wherein it is possible to observe how the model of the technical system to be controlled reacts to the signals of the control unit, and how the control unit reacts to the events predefined by the model of the technical system to be controlled. In this process, it is possible to simulate not only normal operation, but also faults in the technical system to be controlled as well as faults in the control unit.
In contrast, so-called rapid control prototyping (RCP) is a development step that takes place more toward the start of the development process. In RCP, the testing device is used in the role of the control unit. The testing device contains a model of the control unit to be tested. Because of the early stage of development, the model of the control unit to be tested is still fairly rudimentary in comparison to the later, final control unit. Nor is any hardware implementation of the control unit normally in existence yet; instead, the model of the control unit to be tested that is present in the testing device is a software model. The testing device can be connected through an input/output interface to the technical system to be controlled itself, or to the control unit that exists to date for the technical system to be controlled. In the first case, there is a direct connection between the control unit to be tested, in the form of a software model, and the technical system to be controlled, which is physically present. In the second case, the control unit that exists to date is the technical system to be controlled by the RCP testing device. This control of the control unit that exists to date results in a modification of the control method of the control unit that exists to date, making it possible to test new control functionality by means of the externally connected RCP testing device.
In both examples cited (HIL simulator and RCP testing device), there is a testing device in which a model is present, and this testing device must be connected to an external device through the input/output interface so that the test can be performed. In the case of RCP, the testing device contains a model of the control unit to be tested, and is connected to the technical system to be controlled. In the case of HIL, the testing device contains a model of the technical system to be controlled, and is connected to the control unit to be tested. In both cases, a testing device equipped for testing the control unit is provided, wherein in one case the control unit is tested as a model, and in the other case the control unit is tested as a hardware implementation that can be connected externally.
As already indicated, the testing device has an input/output interface through which the testing device is connected to the technical system to be controlled or to the control unit to be tested, depending on the application. This input/output interface is connected in the testing device to the model present in the testing device, so that the model can communicate through the input/output interface with the technical system to be controlled or with the control unit to be tested. For this connection of the model to the input/output interface, the testing device has a plurality of input/output functions. These input/output functions represent the link between the model on one side and the concrete input/output interface on the other side.
One and the same testing device can be used for different simulations. In other words, one and the same testing device can be used with different models present in the testing device and with different control units to be tested, or technical systems to be controlled, connected to the testing device. It is evident that different channels of the input/output interface and different input/output functions are required for different connected devices/systems and for different models. Accordingly, it is customary to produce particular connections between the input/output interface on one side and the input/output connections on the other side prior to carrying out a particular simulation.
Nevertheless, there is as yet no satisfactory method that permits the connection of the input/output interface to the input/output functions with acceptable effort while providing satisfactory adaptation to the individual case.